Quite possibly there is very little or no hum on the recording if it was 
made on a portable recorder because they used batteries and had a DC 
motor. I actually had one of these in the middle 1960's and, IIRC, it 
used "C" cells. It also had an adapter to be used in the cigarette 
lighter of your car where I used this particular recorder. The recorder 
(made in Japan) used 3" reels and was 1/2Tr. mono allowing the tape to 
be recorded in both directions. I permanently mounted leader to the 
take-up reel to facilitate loading & threading so, I would carry 
pre-leadered spare reels. I used the recorder as a dictation machine to 
record the posted information for new construction. I would transcribe 
the tapes using a Roberts deck for playback, listening with headphones. 
I remember my voice being off pitch at the beginning and end of the 
tapes because the Roberts was a constant speed deck. I remember that my 
voice sounded most normal in the middle of the tape when playing back on 
the Roberts which, may be a clue for locating the most accurate pitch.



Corey Bailey Audio Engineering

On 7/12/2019 9:06 PM, Jamie Howarth wrote:
> If there’s hum in the recording or if you like send me a 192/24 sample right from the playback and I’ll see if we can make a quick utility for you.
> Jamie Howarth
> Plangent Processes
> Please pardon the mispellings and occassional insane word substitution I'm on an iPhone
>> On Jul 12, 2019, at 21:58, Tim Gillett <[log in to unmask]> wrote:
>> I'm not familiar with the "gliding stretch" of Adobe Audition but if
>> it allows you to set (by ear or even better by a reference on the tape
>> such as hum) a start speed and  end speed then assuming a linear
>> increase in speed between those two end points, I guess it would
>> replicate the original recorded speed.  I'd first make the assumption
>> that the original recorded speed didn't deviate due to slippage,
>> battery fade etc. Only if the speed was obviously inconsistent after
>> the initial correction of start and end points would I attempt further
>> corrections.
>> It wasn't just cheap/battery powered  machines which used the rim
>> drive system. On the Continent from the mid 1950's,
>> Philips, Grundig and perhaps others used rim drive in mains powered
>> dictation machines  with essentially constant speed AC drive motors.
>> Grundig tended to use their own proprietary tape cassette, and non
>> standard reels, but the Philips models I'm familiar with used two 3"
>> standard 1/4" reels inside a clear "cassette".  The larger inner hub
>> size was used. These machines  come up on Ebay.  Many were
>> valve(tube) based machine. Philips continued the rim drive principle
>> though to a 1/8" tape in another type of cassette, and then on to the
>> tiny "mini cassette", also rim drive.
>> Tim
>> ----- Original Message -----
>> From:
>> "Association for Recorded Sound Discussion List"
>> <[log in to unmask]>
>> To:
>> <[log in to unmask]>
>> Cc:
>> Sent:
>> Fri, 12 Jul 2019 16:41:07 -0400
>> Subject:
>> Re: [ARSCLIST] Reel-to-Reel tape problem
>> Hello, J.D.,
>> I tried thinking this problem through a while ago and it hurt my
>> brain.
>> You've heard from three experts who all said basically the same
>> thing--with which I concur.
>> What I thought I would add is a little thought experiment.
>> These machines did not have a capstan and they pulled the tape by a
>> motor attached to the takeup reel. For some reason it has been
>> referred
>> to as "rim drive" perhaps because the motor often contacted a rubber
>> surface on the rim of the reel table to provide a "gearing" ratio
>> from
>> the motor to the reel table, rather than being directly attached to
>> the
>> spindle.
>> So, let's assume that we have a constant speed motor that can deliver
>> infinite torque (bear with my and hold your "tsk tsks"). If that were
>> the case, you could calculate the actual speed by knowing the radius
>> of
>> the tape pack at time of recording, the speed of the motor and pi. As
>> the takeup reel filled up, the tape speed would increase, so if
>> you're
>> listening on a capstan driven machine, the pitch would drop. Let's
>> call
>> this calculation (A).
>> BUT, the motor does not have infinite torque. As the radius of the
>> takeup reel tape pack increases, the moment arm gets longer meaning
>> that
>> the same amount of holdback tension may cause the motor to slow down
>> a
>> bit as it can't deliver all the torque that would be required. So
>> this
>> adjustment factor could be figured out, but the speed at the end of
>> the
>> tape will fall short of what you calculated in (A) above. Let's call
>> this adjustment factor (B).
>> So, at this point, the speed at any given point is (A) - (B).
>> Now, some odd things enter in that will change this. As the (gasp
>> zinc
>> carbon flashlight) batteries discharge, the motor will not be able to
>> deliver as much torque as the batteries will deliver less current and
>> their voltage will drop compared with fresh batteries, so we have a
>> third factor.
>> And if this unknowable was not enough, the holdback tension was
>> provided
>> by pressure pads--usually against the heads--so this creates multiple
>> additional factors for affecting speed:
>> --the calendaring/polish of both tape surfaces will affect the
>> friction.
>> --the environmental temperature and humidity will affect the
>> friction.
>> --the cleanliness of the guides/heads will affect the friction.
>> So, there you have a quick snapshot of the dynamics of this system
>> and
>> why fixing it in post in software is the best alternative.
>> I reiterate what Ted Kendall said, "there were myriad reel-drive
>> Japanese recorders around at the time, all of which were different
>> between samples, never mind designs." And I might add, there were
>> differences with the same recorder based on tape type, climate
>> conditions, and battery condition. A fair number of these recordings
>> originated in Vietnam in my experience, but thankfully a large number
>> of
>> the ones I have received were recorded with capstan machines. the
>> Craig
>> 212 was a classic of the era with a capstan.
>> Cheers,
>> Richard
>>> On 2019-07-12 3:53 p.m., Scott Phillips wrote:
>>> These would have been rim drive recorders, without a capstan drive
>> roller. There is no fixed speed, it was determined by reel motor
>> torque and the diameter of the amount of tape on either reel at any
>> moment. Good luck with that, software is about your only available
>> practical tool I know of..
>>> Best regards,
>>> Scott Phillips
>>> -----Original Message-----
>>> From: Association for Recorded Sound Discussion List
>> [mailto:[log in to unmask]] On Behalf Of J. D. Mack
>>> Sent: Friday, July 12, 2019 1:30 PM
>>> To: [log in to unmask]
>>> Subject: [ARSCLIST] Reel-to-Reel tape problem
>>> I'm looking for some advice/info. I sometimes transfer reel-to-reel
>> tapes to CD or digital files for my customers. Frequently, I receive 3
>> inch tapes from the 1960s that start at one speed and gradually speed
>> up or slow down substantially as the tape plays. The speed range is
>> usually between 1 7/8 and 3 3/4, but never landing on either speed. I
>> can correct for this using Adobe Audition's gliding stretch, but it
>> takes quite a bit of trial and error. What sort of tape player would I
>> need to hunt down to play these tapes correctly without having to
>> resort to a software solution? My customers never have any idea what
>> brand and model was used to make the recordings.
>> -- 
>> Richard L. Hess email: [log in to unmask]
>> Aurora, Ontario, Canada 647 479 2800
>> Quality tape transfers -- even from hard-to-play tapes.
>> -------------------------
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